• Song Liu's avatar
    perf/core: Fix bad use of igrab() · 9511bce9
    Song Liu authored
    As Miklos reported and suggested:
    
     "This pattern repeats two times in trace_uprobe.c and in
      kernel/events/core.c as well:
    
          ret = kern_path(filename, LOOKUP_FOLLOW, &path);
          if (ret)
              goto fail_address_parse;
    
          inode = igrab(d_inode(path.dentry));
          path_put(&path);
    
      And it's wrong.  You can only hold a reference to the inode if you
      have an active ref to the superblock as well (which is normally
      through path.mnt) or holding s_umount.
    
      This way unmounting the containing filesystem while the tracepoint is
      active will give you the "VFS: Busy inodes after unmount..." message
      and a crash when the inode is finally put.
    
      Solution: store path instead of inode."
    
    This patch fixes the issue in kernel/event/core.c.
    Reviewed-and-tested-by: default avatarAlexander Shishkin <alexander.shishkin@linux.intel.com>
    Reported-by: default avatarMiklos Szeredi <miklos@szeredi.hu>
    Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
    Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
    Cc: <kernel-team@fb.com>
    Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
    Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Stephane Eranian <eranian@google.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Vince Weaver <vincent.weaver@maine.edu>
    Fixes: 375637bc ("perf/core: Introduce address range filtering")
    Link: http://lkml.kernel.org/r/20180418062907.3210386-2-songliubraving@fb.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    9511bce9
pt.c 37.6 KB